Using Co-Registration of Eye Movements and Electroencephalography to Investigate Ageing Effects on Word Recognition during Natural Reading

Reading is an important life skill. Additionally, regular reading in later age may help build up cognitive reserve, thus making us more resilient to effects of ageing or disease. It is therefore important to understand normal ageing effects on cognitive processes associated with reading. Despite this, the focus has mainly been on young adults, and little is known about changes as we age.

Two methods which have been used extensively to investigate reading are electroencephalography (EEG) and eye-tracking. EEG is a non-invasive cognitive neuroscience method which can directly measure neural responses to stimuli. When combined with psycholinguistic theories, cognitive processes can be inferred from timing and magnitude of responses, known as event-related potentials (ERPs). By comparing ERPs across age groups, it is possible to infer whether processing differs. However, this method is limited when studying reading because it cannot accurately determine when eyes are fixated on certain words, and eye movements cause artefacts in EEG data. Therefore, experiments have typically used paradigms with low ecological validity, where one word is presented at a time in the centre of the screen for a fixed period. This does not allow for individual differences in reading speeds and processing of words in parafoveal vision. Conversely, eye-tracking does allow natural reading paradigms to be used. This behavioural method is used to imply where attention is focused and for how long. However, unlike EEG, it does not directly measure neural activity, and thus cannot investigate underlying cognitive processes whilst the eyes are fixated on a word.